Traffic signal control toner sequencer and responder



1964 G. D. HENDRICKS ETAL 3,159,817

TRAFFIC SIGNAL CONTROL TONER SEQUENCER AND RESPONDER Filed Sept. 14, 1959 I s Sheets-Sheet 1 PRIOR ART LI L2 Ll L2 Ll L2 Ll L2 I Ll L2 TR XR FIG.3

I INTERVALS DWELL .I 2 a 4 s s 7 a 9 I0 MOTOR c l cnnavovsn I MULT. TI 02 I I I I TONE 1'2 GIG, l

' I I l I I I TONE 1'3 C9l U N LATCH 1'4 C 8 I I I I I I l I I I 'IIII I /2IIIII SEC. sac. SEC.| SEC. I SEC.5Ec sec. SEC. I sac. SEC. 5E6.

II .I

\I,4 \l I sec. SEC. C5 s. DONALD HENDRICKS 0e THOMAS E. BARTLETT GAR LAND E. IESER a c W' United States Patent TRAFFIC SIGNAL CONTROL TQNER SEQUENCER AND RESPONDER George Donald Hendricks, Camphells Island, llL, Thomas B. Bartlett, Davenport, Iowa, and tSarland E. Fieser, East Moline, 151., assignors, by inesne assignments, to E. W. liiliss Company, Canton, ()hio, a corporation of Delaware Filed Sept. 14, 1959, Ser. No. 839,849 5 Claims. (Cl. 340 171) This invention relates to automatic tone switching, sequencing, transmitting, and receiving, and in particular to apparatus at a master trafilc controller for the automatic switching and sequencing of one or more audio tones for reception at and remote control of a plurality of local traffic signal controllers.

Apparatus which will control the function of a plurality of trafiic control devices from a master control device employing the pulse technique is well known. Examples of such devices are illustrated in United States Patent 2,826,752 and 2,832,060 issued to George Donald Hendricks et al., and in application 473,080 filed December 6, 1954, by George Donald Hendricks now abandoned and continued in the United States Patent 3,005,- 188, entitled Electric Channel Selectors, and assigned to the assignee of the present invention. What is believed to be new is to provide apparatus which employs the tone technique to simultaneously control the operation of a large number of local traffic signal controllers through a plurality of control combinations. Hitherto the signals for the change of each control function had to be sent in turn and could not be sent simultaneously.

A master controller of the computer type with which the invention is adapted to cooperate is illustrated in United States Patent 3,120,651, entitled Traffic Adjusted Traffic Control System and assigned to the assignee of the present invention. The local intersection trafiic signal controllers with which the invention is adapted to cooperate are illustrated in patent application 642,469, filed February 26, 1957, entitled Multiple Program Traffic Control System also assigned to the assignee of the pre ent invention. The subject invention is designed to replace the seven wire interconnection between the master and all local controllers with a two wire circuit or a radio link.

The apparatus of the invention consists of a group of tone generators operating continuously and an automatic sequence timer started through a cycle of operation each time a control condition is changed by the master controller. Several control conditions can be changed simultaneously. Previously, groups of pulses were transmitted for each change required, a different series of pulses being employed for each different function change required. In the new apparatus the sequence represents a complete set of control conditions which are established after the prior control condition has been erased. Thus, when a function change is called for by the master each of the past functions at the local is erased and immediately the new functions are placed in effect.

Another difference between the prior art devices and this device is that the present device employs two frequencies simultaneously, one as a multiplier to double the effect of the other frequencies. The automatic sequence timer, in conjunction with the control relays, closes one or more circuits between one or more tone generators and the output circuit to provide various tone combinations and sequences which cause different effects at the responders. The automatic sequence timer also interrupts the synchronizing tone while the other tones are being sent.

3,159,817 Patented Dec. 1, 1964 "ice The responder at each local controller receives and amplifies the tones, and depending upon the frequency of the tone energizes one or more sensitive relays. The sensitive relays latch or unlatch one or more control relays which switch power to the'output control circuits which energize or deenergize control relays in the local controller.

Functions controlled by each local traffic signal controller consist of trafiiic cycle length and synchronization, traffic cycle split, and traffic cycle offset. In the form of the invention described herein, there are six choices of tratiic cycle length, four independent selections of traffic cycle split, and four independent choices of offset or progression.

The SiX choices of trafilc cycle length may be selected by master and local controller apparatus of the type disclosed in United States Patent 3,047,838, entitled Traffic Cycle Length Selector. The four choices of traffic cycle split may be selected, for example, by master and local controller apparatus such as that disclosed in application 742,160, filed June 16, 1958, and entitled Traffic Cycle Split Selector. The four choices of traffic cycle offset may be selected by master and local controller apparatus of the type disclosed in application 768,193, filed ()ctober 20, 1958, entitled Traffic Cycle Offset Selector. Each of the above patent applications is assigned to the assignee of the present invention.

Cycle length or duration is herein defined as the time in seconds from the beginning of the right of way interval on one street, through the right of way intervals on all other streets at the intersection, until the beginning of the next right of way interval on the first street. Cycle split is defined as the percent division of the complete traflic signal cycle between one street and a cross street. Offset is defined as the percent of a traffic signal cycle that the start of an interval at a local intersection is delayed or advanced from the start of the same interval at the master controller.

The principal object of the invention is to provide a sequential tone transmitter and receiver adapted to permit a master traffic controller to effect control of a plurality of local intersection traffic signal controllers through a large number of control conditions.

Another object is to provide automatic sequencing of the outputs of a plurality of tone generators to an output circuit depending upon the condition of a plurality of control relays.

Another object is to provide a tone sequencing circuit started through a sequence each time a control relay is energized or deenergized.

Another object is to provide a plurality of tone responders, each including an amplifier, a relay having a plurality of contacts each responsive to a different tone, a plurality of sensitive relays energized through the different contacts, and a plurality of control relays controlled by the sensitive relays.

Another object is to provide a five tone sequencing device designed to control nine functions including traffic cycle synchronization, four choices of split, and four choices of offset.

Another object is to provide a sequencing device employing one tone for synchronization, one tone for latch relay release, two tones for two changes of one function, and a multiplying tone for doubling the number of functions controlled.

Another object is to provide a synchronizing tone transmitted for most of each traffic signal cycle and interrupted by the sequencing timer when a function change is transmitted.

Another object is to provide automatic tone sequencing apparatus and a radio transmitter adapted to broadcast a plurality of tones in sequence, and a plurality of local ab radio receivers and tone sensitive devices to remotely control a group of tratiic control functions.

The invention will be described with reference to the following drawings, of which:

FIGURE 1 is a block diagram showing a commonly used multiconductor interconnection beaveen a master controller and a plurality of local controllers.

FIGURE 2 is a block diagram of one form of the invention employing a master controller, tone sequencing apparatus, and a circuit interconnected to a plurality of tone responders and local controllers.

FIGURE 3 is a block diagram of the preferred form of the invention employing a radio transmitter and receiver between the sequencing apparatus and the tone responders.

FIGURE 4 is a wiring diagram of the master tone sequencing apparatus.

FIGURE 5 is a cam chart for the automatic sequencing timer. Each horizontal line indicates a tone output it its control relay is energized.

FIGURE 6 is a wiring diagram of the local tone responsive apparatus.

Before the invention is described, an existing form of interconnection will be described. FlGURE 1 illustrates in block diagram form the present method of traffic cycle controller interconnection in common use today. A master traflic controller M may receive information from two or more tratlic detectors in two or more tratlic lanes and select a most expedient trafi'ic cycle length, split, and offset, and energize one or more control conductor 2025 accordingly. The master controller may also be the type which programs changes in trafiic cycle length, split, and oilset, or may employ any combination of traffic volume controlled and program controlled system.

A plurality of local intersection trafiic signal controllers L are located at street intersections remote from the master controller M. A seven conductor cable CC is installed between the master controller M and each local controller L. Conductor 2i; carries the variable frequency current for traflic cycle length control, conductor 21 carries the synchronizing pulse, conductors 22, 23 carry the traffic cycle offset controlling current, and conductors Z4, 25 carry the trafiic cycle split controlling current. Line L1 is the common return conductor.

The present invention is directed toward the reduction of the number of conductors required in the interconnecting cable CC, and in another form to the elimination of cable CC altogether.

The simplest form of the invention is shown in FIG- URE 2. A master trahic signal controller of the computing or programming type, or any combination thereof, is indicated at M. It is designed to energize one or more of the control conductors 28-25 to thereby eitect control of the local intersection tratiic signal controllers L. In known systems, each of the conductors extends from the master controller M to all of the local controllers L. In the present invention the seven conductor cable is replaced with a pair of conductors over which a plurality of tones are transmitted to each of the local controllers. One of the conductors may be grounded. The conductors may be a pair of wires in an existing cable or may be a leased telephone pai In a new installation a two conductor interconnection is cheaper than a multi-conductor installation. In a new installation a leased telephone pair would probably be more economical than a separate two wire interconnection.

The master tone sequencing apparatus is indicated at TS in FIGURE 2. Its purpose is to translate electric potentials received from the master controller M over conductors 21425 to tones sent for a period of one or more seconds duration each time a control function changes. The series of tones are transmitted over interconnectin conductor CC to each tone responder R, one of which is shown. The tone responders R are designed to amplify the signal received from the master to thus Cit reduce the load imposed on line CC, and to apply the amplified signal to a tone sensitive relay. The relay has a plurality of vibrating reeds each of which makes intermittent contact with a stationary contact when its resonant frequency is present in the incoming signal. Each of the contacts controls a sensitive relay which in turn controls a latching type output relay. The latch relays apply potential to a number of circuits 214.5 connected to control the local controller L. One tone is sent prior to the others to unlatch the relays that are already latched.

The variable frequency which deter tines traflic cycle length is also transmitted to each local controller L from the master controller M over conductor CC. The variable frequency signal is applied to the cathode follower output stage in the tone sequencer TS and is thus applied to conductor CC. At the responder R the variable frequency signal is amplified along with the other tones before eing applied to a novel amplifier A. The ampliher A is designed to supply a voltage to a timing motor, the voltage across the motor being substantially proportional to frequency. The amplifier is described more fully in patent application 830,038 filed luly 28, 1959, entitled Constant Current Traific Control Amplifier, now abandoned. The variable frequency generating apparatus at the master controller is disclosed fully in patent application 830,095 filed Iuly 28, 1959, entitled Remote Control of Tratilc Cycle Length. Each of the above applications is assigned to the assignee of the present invention.

The variable frequency portion of the master and local controllers is not described in this application but is shown in the block diagrams for completeness. The apparatus of this application is limited to function change and synchronization.

In the second form of the invention shown in FIG- URE 3, a standard radio transmitter TR is employed at the master controller and a standard radio receiver XR is employed at each local controller, in place of the interconnecting circuit CC. The output of the master tone sequencing apparatus TS is applied as a modulator of the carrier frequency developed in transmitter TR. The receiver XR demodulates the radio signal received and applies the tone frequencies to the tone responder The remainder of the apparatus is identical with that dcscribed in connection with FIGURE 2.

The variable frequency for controlling the duration of the tratlic signal cycle is also employed as a modulator of the radio carrier frequency and is broadcast by transmitter TR. The radio frequency is detected by the tuned receivers XR and demodulated and the resulting variable frequency is applied to the preamplifier in the tone responder and is then applied to the filter stage of ampliher A. The output is used to drive the trailic cycle timing mechanism within the local controller L.

The master tone sequencing apparatus is illustrated in diagrammatic form in FIGURE 4. The control con doctors 2d and 22-25 originate in the master traific controller and are shown at the left of the diagram. Conductor 2d carries the variable frequency and connects directly to the cathode follower CF whose output is applied to control circuit CC. Conductors ZZJLS control relays CRlCR4. Conductor controls the synchronizing pulse and is shown originating at the synchronizing contacts Conductor Ll connects to return line Ll.

It will ,be noted that line 2.]. in FIGURES 2 and 3 is connected between the master controller M and the tone sequencer TS while in FIGURE 4, line 211 originates at the synchronizing switch 295. In the preferred form of the invention the cam 29 shown in FIGURE 4 is located in the Master Controller M. The output of tone generator T5 is conducted to the master on line 21A and applied to line 231 during approximately 97% of each traffic signal cycle. Line El contracts with the cathode follower CF and the output circuit CC.

Synchronizing power is sent out during approximately 97% of the traffic signal cycle and interrupted during approximately 3% of the cycle. During the interruption a pair of synchronizing contacts may close in each local controller L without braking the dial motor. If any local controller L is out of step with the master M, closure of its resynchronizing contacts energizes a brake and stops the timing dial until resynchronizing power from the master M is interrupted. The local controller L and master controller M then start out together and in step. An example of this type of synchronizing system is shown in patent application 642,469 named above.

The variable frequency line 29 is not controlled by the sequencing timer but is applied directly to the cathode follower CF and thence to the FM transmitter TR for use as a modulating frequency. if a metallic circuit CC is used in place or" the radio transmitter TR, the variable frequency is fed to each local controller on circuit CC.

Control relays CRT-CR4 are of the continuous duty type because one or all of them may be operating for periods of considerable duration. Relays CR1 and CR2 are used in binary combination to obtain four choices of trathc cycle split. if neither relay is energized a first split is in effect. When one relay is energized, a second split is effective. When the other is energized, a third split is in eifect. if both are energized, a fourth split is effective.

Relays CR3 and CR4 are used in binary combination to obtain four choices of trafiic cycle offset. If neither relay is energized, a first offset is in effect. When relay CR3 is energized, a second offset is effective. When relay CR4 is energized, a third offset is in elfect. if both relays are energized, a fourth olfset is effective.

Each of the control relays has three sets of contacts; one set, CRlBCldB close a holding circuit to a group of slow release relays CR5CR8, a second set, CRlA- CR EA transfer to close a circuit to the sequencing timer motor Ml, and a third set, CRlC-CRiC close circuits from the tone generators T2, T3 to the cathode follower CF and output circuit CC.

The automatic sequencing timer T consists of a motor M1 which, through gearing, not shown, rotates a camshaft upon which a plurality of cams Cl-Cltl are mounted. Each of the cams Cll-Cltl controls one of the switches S1Sl. The switches SL819 may be in the form of individual snap acting switches. The mechanical aspects of the timer are omitted from the drawings as they are Well known and commonly used.

Switch Si provides a holding circuit for timer motor Nil. Switch S2 controls a multiplying relay CRM. Relay CRM is termed a multiplying relay because it doubles the number of functions which may be controlled by the apparatus. In a deenergized condition a first group of functions are controlled; in an energized condition, a second group of functions are controlled.

Switches S3S6 provide temporary energization paths for the slow break relays CRS-CRS, respectively. Switches S"7S3ltl, in conjunction with the control relay contacts, control the duration and timing of application of the various tones T5T2, respectively, to the cathode follower CF and output circuit CC.

Operation The operation of the automatic tone sequencing apparatus will now be described. -Reference will be made to FIGURE 5 for timings of cams Cl-Cli) and switches SlSl0. Assume, for examplathat none of the control relays CRiCRd is energized and that the timer Thas completed its cycle of operation and is at rest in the dwell interval. Only switch S7 is closed permitting the synchronizing tone from tone generator T5 to pass over conductor 21A, through the synchronizing switch 298, through line 21, to the cathode follower CF, and to output circuit CC. Although the other tone generators T1-T4 are operating, none of their switches SS-Slt) or control contacts are closed and none of the tones reach the oathode follower CF. Thus, the trafiic cycle split and traffic the ratio of main street to cross street traffic volumes and.

energizes line 24 to effect a change in trailic cycle split at the local controllers L. Split control relay coil CR1-C is energized. lt transfers contacts CRIA, and closes contacts CRIB and CRlC.

When contacts CRlA transfer they provide a path for temporarily energizing timer motor MT. The path ineludes line L2, line 31, now-transferred contacts CRlA, contacts CRSA, line 32, motor M1, line 33, and line L1. Motor M1 rotates the camshaft and cams C1-C1t! which control switches SLSTS. Switch S1 closes almost imme diately and provides a motor holding circuit through line L2, line 34, now-closed switch S1, line 35, to motor Ml. Cam C1, FIGURE 5, is cut to permit switch S1 to be closed for almost an entire revolution of the camshaft and permits motor M1 to drive the camshaft a full revolution each time the motor is temporarily energized.

When contacts CRlB close they close one gap in a circuit to slow brealc relay coil CR5-C. During interval 1 of the sequencing timer T, cam C6 permits switch S6 to transfer for approximately one second and provide a path for energizing relay CR5. The path includes line L2, rectifier RDll, line 36, now-transferred switch S6, line 41, now-closed contacts CRlB, line 45, relay coil CR5-C, line 37, and line Ll. Relay contacts CRSB close and when switch S5 transfers back to the position shown in FTGURE 4 a holding circuit is completed. The circuit includes line L2, rectifier R131, line 36, switch S6, line 51, now-closed contacts CRSB, relay coil CRS-C, line 37, and line L1. Contacts CREE remain closed while switch S6 transfers from the energizing position to the holding position because relay CR5 is a slow break relay. its delay period may be approximately one-half second.

Contacts CRSA transfer and open the temporary energizing circuit to motor M1. Motor M1 does not stop ecausc it is being energized through switch S1. Cont'acts CRSA are provided to interrupt the motor starting circuit.

Relay CR5 will remain energized until control line 24 from the master controller M is deenergized. Line 24 will remain energized until traffic volumes change and the traffic cycle split must be changed. In going from the condition in which control conductor 24 is energized to the condition in which both control conductors 24 and 25 are to be energized, no change is made in the condition of relays CR1 and CR5. Only the condition of relays CR2 and CR6 is changed: they both become energized.

Returning to the description of the operation of the sequencing apparatus, timer T has timed into interval 1 and cam C2 permits switch S2 to close and energize the multiplying relay CRM. The path of current is from line L2, line 38, switch S2, line 39, multiplying relay coil CRMC, and line L1. Contacts CRMI and CRMZ transfer and contacts CRM3 close.

The transfer of contacts CRMl has no effect because control relay contacts CRZC and CR4C are open. The transfer of contacts CRM2 has no effect because control contacts CRSC are open. The closure of contactsCRMYa permits the output of tone generator T1 to flow to the cathode follower CF and output circuit CC. At the local tone responder the multiplying tone has no effect when transmitted alone.

When timer T times into interval 2, cam C8 closes switch S8 and permits the output of tone generator T4 to flow through line 53 to the cathode follower CF and output circuit CC. At the local tone responder this unlatches any offset controlling relay. Since it was assumed at the start of the explanation that all condoctors 22-25 were dead and thus none of the split or offset control relays are latched in, the unlatching of the offset control relays has no effect.

When the timer T times into interval 3, cam C9 closes switch S9 and permits the output of tone generator T3 to flow through line 59 to now-transferred contacts CRMl. The signal cannot flow to the cathode follower CF because contacts CR lC are open.

In interval 4, cam Cid permits switch Slit to close and permits the output of tone generator T2 to flow through line 6% and now-transferred contacts CRMZ. Since contacts CREC are open, the signal cannot reach the cathode follower CF.

The multiplying frequency is permitted to flow for a short period during interval 5 to make the setting of cam C2 less critical. During intervals 6 through it switch S2 is open and the multiplying relay CRM is deenergized. Contacts CRM3 open and contacts CRM]. and CRMZ; transfer back to the position shown in FIGURE 4.

During interval 6 none of the tones is transmitted so that a separation will exist between the offset controlling tones and the split controlling tones. During interval '7 cam C8 again permits switch S3 to close. The knockdown tone passes through switch SS, through line 53, to the cathode follower CF and output circuit CC. Since none of the split controlling relays in the local tone responders are energized, the knockdown frequency makes no change in their position.

During interval 8 cam C9 closes switch S9 and permits signal from tone generator T3 to flow through line 5'9, through contacts CRME, to contacts CRZC. Contacts CRZC are open and the signal cannot flow to the cathode follower CF.

During interval 9 cam Cltl closes switch Sid and permits signal from tone generator T2 to flow through line (it), through contacts CRMZ, through now-closed contacts CRllC, to the cathode follower CF and output circuit CC. At the local tone responders a first split control relay is energized and latched in. It places continuous power on a first split controlling line. Thus, when the master controller calls for a change in traiiic cycle split, the change is made a few seconds later at all local controllers.

Timer T times interval 16) during which no tones are transmitted, and comes to rest in the dwell interval when cam C1 opens switch S1 in the motor holding circuit. Cam C7 permits switch S7 to close so that the synchronizing tone from tone generator T5 is applied to the synchronizing switch 298 through line 21A. Since switch 298 is closed during the greater portion of each traffic signal cycle, the synchronizing signal is applied through line 21 to the cathode follower CF and output circuit CC. A timer in the master controller M may open line 21A after each function change that requires the local controllers to get into step. This reduces the amount of time the synchronizing current need be transmitted.

Assume now that the master trafiic controller determines from tramc volumes that the traffic cycle split should revert to the split which was first in effect. It deenergizes control line 24 and relay coil CR1lC. Contacts CRlB open but have no effect because switch S6 in series with them is already open. Relay coil (IRE-C is receiving power from line L2, rectifier RDl, line 36, switch S6, line 51, and contacts CRSB.

Contacts CRiA retransfer to the position shown in FIGURE 4, and since contacts CRSA are still transferred, a temporary path is provided to energize timer motor T. The circuit includes line L2, line 31, still-transferred contacts CRSA, contacts CRlA, line 32, motor M1, line 33, and line Ll.

Motor M1 rotates the timer camshaft and almost immediately cam Cl permits switch S1 to close the motor holding circuit. Cam C6 causes switch S6 to transfer and this breaks the holding circuit for slow break relay coil CREE-C. Switch S6 remains transferred longer than the release time of relay CR5. Thus, contacts C1258 open before switch ss ret'ransfers to the position shown in FIGURE 4. The timer times through intervals 1 to 6 as described above with no effect on the offset control relays at the local tone responders.

in interval 7, switch S8 closes and permits the knockdown signal from tone generator T4 to pass through line to cathode follower CF and output circuit CC. At each local tone responder the split control relays unlatching coils are energized. Since only the one split control relay is latched in, it is the only relay affected. Being unlatched, it removes power from the first split control conductor, and the traiiic cycle split reverts to that originally in effect when no split control conductor was energized.

The energizing and holding circuits for the slow break relay coils CR5-C to CRSC are designed to operate in conjunction with the sequencing timer T to provide a memory circuit that starts timer T through a sequence when a control conductor is energized and again when it is deenergized. This, in conjunction with the latch type clays in each tone responder, makes it possible for the system to send tones intermittently and not continuously. This makes it possible to utilize the time between function changes for synchronizing purposes. It also reduces the time that radio signal is broadcast and thus reduces interference with other communication in the same band. The variable frequency for adjustable control of trafiic cycle length is broadcast continuously using another intermediate frequency but the same carrier.

The circuit is designed so that only two function control tone frequencies need be transmitted at any one time. This insures accurate response at each responder. If more frequencies were transmitted simultaneously there would be a greater possibility that the wrong reed would vibrate sufiiciently to energize its sensitive relay. Further, the number of stages of amplification and the cost of the amplifier has been reduced to a practical minimum. Cost is an important factor where a large number of tone responders is involved, as with the present invention.

Second Split Control Conductor Assume now that the master traiiic controller M senses a change in the ratio of trafiic volumes on intersecting streets and determines that a third traiiic cycle split should be in effect. Assume also that thetraffic cycle split previously in eflect requires neither conductor 24 nor 25 to be energized. Thus, the sequencing timer T is in the dwell interval and none of the relays CRT-CR4 or (IRS-CR3 are energized.

When conductor 25 is energized by the master controller M, it energizes split control relay coil CR2C. Contacts CRZA transfer and contacts CRZB and CRZC close.

Contacts CRZA provide a temporary energizing path for timer motor MT. The path includes line L3, line Ell, now-transferred contacts CRZA, contacts CRoA, line 32, and motor Ml. Motor: Mil rotates the camshaft and cam Cl allows switch S1 to close and provide a continuous circuit for motor M1 for one revolution of the timer camshaft.

Cams C3-C6 permit switches S3-S6 to transfer for approximately one second. Switch S5 is the only one of the four switches which is effective because only contacts CRZB are closed. Switch 55 applies power to relay coil ens-c. The circuit includes line L2, line 33, rectitier RDl, line 36, now-transferred switch S5, line 42, now-closed contacts CREE, line 46, relay coil CR6-C, line 37, and line Ill.

When relay coil CR6-C is energized, it causes contacts CRdB to close and contacts CR6A to transfer. The closure of contacts case has no immediate eitect because switch S5 is still transferred. The transfer of contacts CRoA breaks the motor initiating circuit made by contacts CRZA but this has no immediate effect on motor Ml because switch ST is closed to hold the motor energized for one revolution of the timer camshaft.

Approximately one second after. switch S transfers and energizes relay coil CR-C it retransfers and closes the circuit to retain relay coil CR6C energized. The circuit includes line L2, line 38, rectifier RD1, line 36, switch 85, line 52, now-closed contacts CRtiB, coil CR6C, line 37, and line L1. Relay CR6 does not open its contacts during this rapid transfer because it is a slow break relay.

Also during interval 1 switch S2 closes and energizes the multiplying relay coil CRM-C. During interval 2 switch S8 closes to permit the knockdown tone signal to flow. During interval 3, switch S9 closes but the tone does not reach the output stage because contacts CR4C are open. During interval 4, switch S closes but the tone does not reach the output stage because contacts CRSC are open.

During interval 5 only the multiplying tone is present. In interval 6 no tone is present. During intervals 6 through 10 switch S2 is open and the multiplying relay CRM is deene-rgized. Contacts CRM3 open and contacts CRM! and CRM2 retranster to the position shown in FIGURE 4. In interval 7 the knockdown tone is present because switch S3 is closed. Since the multiplying tone is absent, the knockdown tone unlatches only the traffic cycle split control relays and not the offset control relays.

During interval 8 switch S9 closes and permits the signal from tone generator T3 to flow over line 59, contacts CRMl, now-closed contacts CRZC, to the cathode tollower CF and output circuit CC. At the local tone responders this tone pulls in the second split control relay and makes that trafiic cycle split effective.

During interval 9 switch S10 closes but no signal flows from tone generator T2 because contacts CRIC are open. During interval 10 no output occurs. The timer T comes to rest in the dwell interval. Thus, a new trafiic cycle split is put into effect in an automatic sequencing cycle which takes approximately 12 seconds to complete. Note that the knockdown tone for the split and the offset are each sent immediately prior to the split controlling tones and the ofiset controlling tones so that a blank is not left between the knockdown tone and the control tone.

One general type of local trafiic signal controller apparatus designed for control by the present tone sequencer and responder is shown in the above mentioned patent application 642,469 entitled Multiple Program Traific Control System. One specific type of local split control apparatus designed for control by the present invention is disclosed in the above named patent application 742,160 entitled Traffic Cycle Split Selector.

Trajfic Cycle Ofiset Control The operation of the ottset control portion of the circuit is similar to that of the split control circuit described immediately above. When the master traffic controller M senses that an appreciable change has occurred in the ratio of inbound to outbound traffic volumes it may demand a different tratfic cycle offset than now in effect. Assume, for example, that the offset in effect was the one requiring neither of the offset control conductors 22,23 to be energized, and the new offset is the one requinng conductor 22 to be energized.

When the master controller M energizes conductor 22, relay coil CRSC is energized. Contacts CR3A transfer, and contacts CRSB and CRZiC close. Contacts CR3A supply a path for temporarily energizing timer motor T which rotates the camshaft and closes switch S1 to provide a holding circuit. When switch S4 transfers it provides an energizing path for relay CR7. The path includes line L2, line 38, rectifier RDl, line 36, now-transferred switch S4, line 43, now-closed contacts CRSB, line 47, relay coil CR7-C, line 37, and line L1.

Cir

During interval 2, the multiplying tone and the knockdown tone are both permitted to reach the cathode follower CF and the output circuit CC. The circuit for the multiplying tone includes tone generator T1, line 61, now-closed contacts CRM3, cathode follower CF, and output circuit CC. The path for the knockdown tone includes tone generator T4, switch S8, line 58, cathode follower CF and output circuit CC.

At the local tone responders R the knockdown tone energizes the unlatch coils of the oiiset control relays but this has no effect on them because they are already unlatched.

During interval 3 switch S9 closes but the output of tone generator T3 cannot reach the output circuit CC because relay contacts CR4C are open.

During interval 4 switch S10 closes and permits the output of tone generator T2 to pass over line 6 3, through now-transferred contacts CRMZ, now-closed contacts CRBC, cathode follower CF, and output circuit CC. At the tone responders R a latching type olfset control relay is momentarily energized and latched in the on position applying power to the local otTset control mechanism. Thus, the new offset is placed in effect.

During the second half of the cycle timed by timer T no change is made in the split control relays. Whatever split control conductor 24, 25 was energized remains energized. if a change had occurred in the condition of one or both of the split control conductors 24, 25 during the timing of timer T the change in split would have been delayed until timer T times through the dwell interval and into interval 1 where switches 83-86 are transferred. The transfer of switches 831% is required to energize the slow release relays CR5 or CR6. Thus, a function change cannot be forgotten.

Second Offset Control Circuit The operation of the second offset control circuit is similar. When the master controller M energizes control conductor 23, relay coil CR4C is energized. Con tacts CRdA transfer and contacts CR4B and CR4C close. Contacts CR4A provide a temporary energizing path for timer motor M1. The timer T times into interval 1 and switch S1 closes to provide a motor holding circuit; Switches S366 transfer. Switch S3 closes the energizing circuit to slow break relay coil CR8C. The circuit includes line L2, line 38, rectifier RDl, switch S3, line 44, contacts CR tB, line 48, relay coil CR$C, line 37, and line L1. After one second switch S3 retransfers to establish a holding circuit. The holding circuit includes line L2, line 38, rectifier RDl, switch S3, line 54, nowclosed contacts CRSB, relay coil CR8-C, line 37, and line L1.

The sequence of tones transmitted when the second ofiset control conductor 23 is energized consists of a muitiplying tone T1 during intervals 1 through 5, a knockdown tone during interval 2, and the tone T3 during interval 3. The path for the tone T3 signal includes tone generator T3, switch S9, line 59, now-transferred contacts CRMi, now-closed contacts CR4C, cathode follower CF and output circuit CC.

The presence of tone T3 in conjunction with the multiplying tcne T1 at the local tone responders R causes the second local offset control relay to be energized into its on position and to energize local control conductor 23.

During the time between changes in traffic cycle split and offset the sequencing timer T rests in the dwell interval with switch S7 closed. This permits the synchronizing tone from tone generator T5 to flow through switch S7, line 21A, synchronizing contacts 298, line 21, to the cathode follower CF and output circuit CC. Contacts 29S are closed during the major portion of the trafiic signal cycle, approximately 97 percent of the cycle. At the local controllers L the pulse is employed to retain the traffic cycle timing dials in step with the gra er? ll master M. During the transmission of trafiic cycle split and offset control tones, the synchronizing tone is interrupted to avoid having more than two function control tones transmitted simultaneously.

It will benoted that once a function change has been completed, no additional tone sequencing is done until a new function change is demanded by the master controller. However, if the system is operating with offset control conductor 22 energized, for example, and offset control conductor 23 is then energized, the first offset control relay will be unlatched at the start of interval 2 and reenergized and relatched at the start of interval 4. If the system is operating with offset control conductor 22 energized, for example, and split control conductor 24 is then energized, the first offset control relay will be unlatched during interval 2 and reenergized and relatched during interval 4. The first split control relay will then be energized and latched during interval 9. In summary, each time a function change occurs, all the relays which were latched are unlatched, and the relays which are to be energized are subsequently energized. The local controllers do not lose step or misc ntrol during the short interruption.

Local Tone Responder Having described the operation of the automatic tone sequencer and the master controller, the operation of the local tone responders and local trafiic signal controllers will now be described.

One of the tone responders R is shown in diagrammatic form in FIGURE 6. It consists of an input channel CC, an amplifier A3, a cathode follower CF3, a tone responsive relay TRS, a plurality of sensitive relays CRll-CRlS, a multiplying relay cars, four latch relays CRlLCRZt and six output terminals 2tl-25'.

The function of the tone responder R is to receive a plurality of audio frequency signals from the master tone sequencer TS over interconnecting conductor CC or from the radio receiver XR and convert the signals for their various uses. The Variable frequency signal for cycle length control is amplified in amplifier A3 and cathode follower CPS and applied to output line 2%. The synchronizing tone is likewise amplified and applied to tone sensitive relay TR3. One contact on relay TR5 energizes a sensitive relay which closes a contact and supplies local power out on line 21' during 97% of the traffic signal cycle. The intermittent function control tones are likewise converted to a steady local power output on the control conductors 2225.

As shown in FIGURE 2, when conductor 22 between the master controller M and the tone sequencer TS is energized by the master controller M, then conductor 22 between the tone responder R and the local controller L is energized by the tone responder R. When power is placed on line 235 by the master controller M, then local power is placed on line 25 to the local controller L by the tone responder R.

The circuit shown in FIGURE 6 will now be described in greater detail. Amplifier A3 is coupled to the interconnecting circuit CC through coupling capacitor C11 which is of small size to reduce loading of the interconnecting circuit CC. The other side of capacitor C11 is connected to ground through variable resistor R1. The center tap of resistor R1 is adjustable and provides proper grid voltage to the grid of amplifier tube V3. Resistor R2. is a grid resistor. Tube V3 is self biased through cathode resistor R3 and capacitor C12 which are connected in parallel between the cathode of tube V3 and ground. A direct current potential is applied to the plate of tube V3 through plate resistor R4. ft is supplied from line L2, rectifier SR1, capacitor C13 and line 13+.

As the voltage of the interconnecting circuit CC varies with the input signal, the voltage appearing at the grid of tube V3 also varies. The voltage fluctuations are amplified by amplifier A3 and are applied to the grid of tube V4 through coupling capacitor C14. Resistor R5 is a grid leak resistor. Tube V4 is connected as a cathode follower through cathode resistor R6. Birect current is applied to the plate of tube V from line B+ through inductance L. The voltage difference appearing across cathode resistor R6 is applied to the coil TR3-C of tone responsive relay TR3 through capacitor C15. The LC circuit consisting of the inductance of coil TR3-C and the capacitance of C15 serve to sustain and augment the amplification of tubes V3 and V4. The value of capacitor C15 is chosen so that resonance is not reached and the circuit does not oscillate. The variable frequency signal for cycle length control is taken elf below inductance L and applied to control conductor Ml.

Tone responsive relay TR5 consists of a driving coil TR3-C and a group of vibrating reeds 1145 each cut to the proper length to resonate at elected frequency. When a reed vibrates with sufficient displacement it makes intermittent contact with a stationary contact and energizes a sensitive relay. Reeds 11-15 are cut to resonate at the frequency of tone generators Tl-T5, respectively. A resistor Rll-Rllfi is connected in series with each sensitive relay coil to limit the current through the reed contacts. Capacitors Cl6CIil are each connected in parallel with sensitive relay coils CRll-CRlS, respec tively, to sustain the current flow through each coil during the half cycles when the voltage of line B-}- is interrupted by the reed contacts.

Sensitive relays CRll-Clll l each have a pair of normally open contacts Chill-l to CRl-l-ll each of which control one or more additional relays. Contacts CRll-l control the multiplying relay CRllfi. In the unenerg-ized position of multiplier relay contacts curs-s, contacts CRl2-l control the first split control relay CRlS. In the energized position of multiplier relay contacts CRlt6-3, contacts CRll2l control the first offset control relay CRZti.

in the unenergized position of multiplier relay contacts care-2, contacts CR131 control the second split control relay CRl7. In the energized position of multiplier relay contacts CRlti-Z, contacts CRl3l control the second offset control relay CRl".

Contacts CRl -l, in the unenergized position of multiplier relay contacts CRll-l, control the release coils CRliR, CRlSR of split control relays CRll7, CRIS. in the energized position of multiplier relay contacts CRlS-l, contacts CRlt-l control the release coils CR19R, CRZtlR of offset control relays CRIS CRZG.

Each of the latching type relays CRll-CRZt) control one of the split control or offset conductors 22 2 5 leading to the local controller L, FTGURE 2. When the main coil of any of the latching type relays CRli-CRZQ is energized it closes its load contacts CRl'7-1 to CR2tll, respectively, and completes a circuit between line L2 and control conductors 25'22', respectively. The relay latches in and its load contacts remain closed after power is removed from the main coil. The release coil must be energized before the load contacts can be opened and the outgoing control circuit denergized.

Operation of Tone Responder The operation of the tone responder is as follows: the variable frequency and one or two function control frequencies may be applied to the grid of amplifier A3 over the incoming channel CC. The signals are amplified in amplifier A3 and in cathode follower CPS. The variable frequency signal is applied to control conductor 20 and the function control signals ener ize the coil TRS-C of tone responsive relay TRS. Que or two of the reeds 1145 will vibrate and close circuits to one or two sensitive relays. The reeds which vibrate will correspond to the input frequencies. The sensitive relays which are energized will in turn energize one of the function control relays and the multiplying relay CRM if the multi- 13 plying tone is present. The function change demanded by the master controller M is thus put into effect.

To trace the first function change described in the section explaining the automatic tone sequencer, assume, for example, that none of the split or offset control relays CR1'7CR2 are latched and that none of the split or offset control conductors 22-25 are energized. Thus, the traffic cycle split and offset which are in effect when none of the control conductors 22'25 are energized are now in effect.

Assume now that the master controller senses that the ratio of trafiic volumes on a grid of intersecting streets has changed sufficiently to call for a second traffic cycle split and that it has urged the automatic tone sequencer to transmit a portion of the tone sequence shown in FIG- URE 5. The sequence consists of the knockdown tone T4 and the tone T2 for the first split change.

Each of the tone responders R receive the two tones in the sequence in which they were transmitted. The first tone T4 is amplified in amplifier A3 and cathode follower CR3 and energizes coil TRB-C. Only reed 14 vibrates sufficiently to close the 13+ circuit to sensitive relay CRM. Contacts CR141 close and apply power from line L2, through contacts CRl-l, to the release coils CRi'iR, CRlSR of latch relays C1117, The energization of release coils CR1'7R, CRlSR has no effect on the output of relays CRY), CRiti because they are already unlatchcd.

When the knockdown tone expires after a one second transmission, reed 14 stops vibrating, relay CR14 loses its source of power, contacts CRM-l open, and release coils CR17R, CRISR are deenergized.

When the second tone T2 is applied to the amplifier A3 and cathode follower CPS it energizes tone coil TR3C at a frequency for which reed 12 is cut. Reed 12 vibrates sufficiently to close the 13+ circuit to sensitive relay CR12. Contacts CR12-1 close and feed power from line L2, through contacts CR121, through contacts CR163 to the latch coil CRISC of relay CR18. Relay CRIS becomes energized and closes contacts CRIS-1. Contacts CRlS-l allow power to flow from line L2, through contacts CR18-1, through control line 24, to the split control circuit in the local controller L. In the local controller L the split control relay connected to incoming line 24 is energized to make effective the new split selection. The split control relays in each local controller may be arranged to provide a first trafiic cycle split when neither relay is energized, to provide a second split when the first relay is energized, to provide a third split when the second relay is energized, and to provide a fourth split when both split control relays are energized. An example of this type of mechanism is shown in patent application 742,160 named above.

If the master controller M senses a change in the ratio of traffic volumes and demands the traf'fic cycle split which was first in effect, it deenergizes line 24 to the automatic tone sequencer TS. This sets the sequence timer T in motion in the manner described in the section entitled Operation. During intervals 1 through 5 of the cam chart shown in FIGURE 5 the multiplying tone T1 is transmitted and in intervals 2 and 7 the knockdown'tone T4 is transmitted. The multiplying tone T1 and the knockdown tone T4 transmitted during interval 2 have no effect because neither of the offset control relays CR19, CRZO is latched in. The knockdown tone T4 transmitted in interval 7 is effective to unlat ch the split control relay CRIS, and conductor 24 to the local controller L is thus deenergized. The traffic cycle split at the local controller L reverts to that in effect when neither of the split control conductors 24', 25' is energized.

The change in traffic cycle offset from one offset to another is similar to the change in trafiic cycle split described above. The exception is that the multiplying tone TI is present to distinguish the change in offset from a change in split.

Assume, for example, that neither of the offset control conductors 22, 23' is energized and there is a change in the ratio of inbound to outbound traffic volumes. The master controller M may energize offset control conductor 22 to the tone sequencer T8. The sequence timer T is started through a cycle of operation and during intervals 1 through 5 transmits tones T1, T4, and T2 shown in the camshaft diagram in FIGURE 5.

At each of the local tone responders R the tones are amplified and passed to the tone coil TR3-C of the tone responsive relay TR3. The presence of tones T1 and T4 in combination energizes the release coils CR19R, CRZflR of oifset control relays CR19, CRZG. Tone T1 causes reed 11 to vibrate sufficiently to intermittently complete the B+ circuit to sensitive relay CR11. Contacts CR111 close and apply power from line L2, through contacts CR111, to energize the multiplying relay CR16. Contacts CR161, --2, and -3 transfer. Tone T4 causes reed 14 to vibrate sufficiently to intermittently complete the B+ circuit to sensitive relay CR14. Contacts CR14-1 close and apply power from line L2, through contacts CRM-Il, through now-transferred contacts CR16-1, to the release coils CR19R, CRZOR of the offset control relays CR19, CR20. Since both relays are already unlatched, this has no effect on the offset control conductors 22', 23.

During interval 3 only the multiplying tone T1 is received and relay CRIS remains energized. During interval 4, signals from tone generators T1 and T2 are received through interconnecting circuit CC. The signal is amplified in amplifier A3 and cathode follower CF3 and applied to the tone coil TR3-C of tone responsive relay TR3. Reeds R11, R12 vibrate sufficiently to intermittently close the 13+ circuit to sensitive relays CRll, CR12. Thus, relay CR11 remains energized and relay CR12 pulls in. Contacts CR11*1 maintain the L2 circuit to the multiplying relay CR16 and contacts CR12-1 close the circuit to the offset control relay CRZO. The circuit includes line L2, now-closed contacts CR121, now-transferred contacts CR16-3, and relay coil CRZtiC. Contacts CR2G-1 close and apply L2 power to offset control line 22 connected to the local controller L. The trafiic cycle offset in effect when line 22' is energized is now placed in effect.

The local controller L starts to put the new traffic cycle offset into effect immediately but may require one or more trafiic signal cycles before the full offset is complete. An example of the local offset control apparatus is disclosed in patent application 768,193 named above.

Syncl'u'onizing Current A synchronizing tone is permitted to flow to the cathode follower CF and the output circuit CC from tone generator T5 through synchronizing switch 298, FIGURE 4. Switch 2%5 is controlled by cam 29 which is driven by the master controller M to make one revolution during each traffic signal cycle. Switch 298 is closed for approximately 97% of each traffic signal cycle and thus provides a synchronizing tone during most of each cycle. The tone is interrupted for a short interval in each trafiic signal cycle to permit any local controller which had been out of step with the master controller to start at the proper time in the cycle.

The synchronizing tone is received at each local tone responder R shown in FIGURE 6 over interconnecting circuit CC or from the radio receiver XR. The signal is amplified in amplifier A3 and cathode follower CF3 and passed to the tone coil TR3C. Reed 15 vibrates sufficiently to intermittently close the circuit from the B+ line and to energize sensitive relay CRIS. Contacts CRIS-1 close and supply steady power from line L2, through line 21B, through now-closed contacts CRIS-1, to control line 21. Line 21 connects to the local controller L and supplies power to potentially energize a relay and interrupt power to the traffic cycle timing motor l. if'it gets out of step with the master M. The timing motor and relay are not shown here but are shown in patent application 642,469 named above.

The synchronizing tone is interrupted for approxinrately 3 percent of each traffic signal cycle. During the interruption relay CREE is deenergized and contacts CRl5ll open. Control line 21 is deenergized and the synchronizin relay within local controller L is deenergized. A synchronizing switch within the local controller L will close during the interruption if the local controller is synchronized with the master. Since the synchronizing line 21 is deenergized during this time, the closure of the synchronizing switch is ineffective to energize the relay and interrupt power to the timing motor.

If the local controller is out of step with the master, the synchronizing switch will close while line Zl is energized and the relay will be energized and interrupt power to the timing motor. The motor will not start until line 21 is deener ized. Deenergization of line 21 will deenergize the relay and permit it to close its contacts and reenergize the timing motor. The local controller and the master will then start out in step.

The synchronizing tone is discontinued when any of the split or offset control or release functions are being transmitted. This is done to limit the number of tones being transmitted at any time and is accomplished by the sequencing timer T, FIGURE 4. Cam C7 opens switch S7 almost immediately after the timer starts operating. This breaks the circuit between tone generator T5 and the cathode follower CF and insures that the synchronizing tone will not be transmitted with the function control tones. Nothing njurious would occur if the synchronizing tone were transmitted with the function oontrol tones but the amplifier A3 in each tone responder R does not have the capacity required to provide suiticient voltage to operate the tone coil TRS-C at three frequencies simultaneously.

The synchronizing tone is transmitted only for a time after each start up of the traffic control system or after power is restored following a power failure. The tone may also be transmitted at intervals throughout the day to ensure that all local controllers are in step with the master.

Representative frequencies employed for the various tones are:

Tone Frequency, cycles per second T3 326.0 T4 255.4 T5 226.0

The variable frequency applied to line Ed is a 2,220 cps. signal amplitude modulated with the cycle duration determining frequency which is variable in increrents between c.p.s. and 90 c.p.s.

The invention has been described in terms of the apparatus disclosed. This is done by way of explanation and not by way of limitation. One skilled in the art may make many changes in the arrangement of the apparatus and in the apparatus itself without departing from the spirit of the invention as set forth in the ap pended claims.

We claim:

1. A tone sequence timing and switching circuit comprising a plurality of function control conductors energizable into a number of control combinations, a like plurality of function control relays connected to said function control conductors, a like plurality of slow break relays each having an electric latch circuit and an electric unlatch circuit, a sequence timer having a plurality of timed control channels and a drive motor, a motor starting circuit including contacts closed when one of said function control relays is energized and including other contacts interrupted when a corresponding one of said "iii slow break relays is energized, each of said electric latch and unlatch circuits including one of said timed control channels, and an output circuit including an output terminal, a plurality of tone generators, a plurality of normally open parallel paths between said output terminal and said tone generators, each said path including one of said timed control channels and at least one other contact controlled by said function control relays.

2. An automatic tone sequencing device including a plurality of audio signal generators, a timer having a plurality of time controlled channels and driving means therefor, a timer starting circuit comprising a plurality of parallel paths in series with a. source of power, a timer running circuit including one of said time controlled channels in series with said source of power, a plurality of function control relays each having at least three ets of control contacts, a like plurality of slow break relays each having an energizing circuit and a holding circuit, each of said energizing circuits including one of said time controlled channels and a first set of said control contacts closed when one of said control relays is energized, each said slow break relay having a set of holding contacts and a set of timer starting circuit interrupter contacts, an output circuit, a plurality of audio signal circuits each including said output circuit and one f said audio signal generators and one of said time controlled channels and one of the second set of said control contacts, and said parallel paths in said timer starting circuit each including the third set of said control contacts and a. set of sad timer starting circuit interrupter contacts.

3. For use with a master controller having function control ouput circuits energizable into a plurality of function control combinations, an automatic tone sequencing device including a plurality of control relays each one connected to one of the function control circuits and energizable therefrom, a like plurality of slow break relays, a plurality of time controlled transfer switches, circuit means including one of said transfer switches and contacts on one of said control relays connected to energize one of said slow break relays after its corresponding control relay is energized and its corresponding transfer switch is transferred, a like plurality of motor starter circuits each including contacts on said control relays closed when the corresponding control relay is energized, a like plurality of starter circuit interrupter contacts on said slow break relays connected to open said motor starter circuit when said slow break relays are energized, a motor holding circuit including one of said time controlled transfer switches closed after said motor is started, a plurality of audio frequency signal generators, an output circuit and a plurality of output paths each including one of said signal generators and one of said time controlled transfer switches and one other of said contacts controlled by said control relays.

4. A device as in claim 3 including a doubling relay connected to be energized through one of said time contnolled transfer switches during a portion of each sequence timed by said sequencing device, one other signal generator and one other output path including a pair of normally open contacts connected to apply the output of said signal generator to said output circuit, and a plurality of transfer contacts in said output paths tran ferred when said doubling relay is energized to thereby half the number of signal generators required to control a given number of functions with said device.

5. An automatic tone timing and sequencing circuit started into a cycle of operation each time a control condition changes, a plurality of function control conductors remotely energizable and deenergizable into a plurality of control combinations, a plurality of function control relays individually connected to said function control conductors, a plurality of slow break relays each having a latch circuit and an unlatch circuit, a sequence timer having a plurality of timed control channels and timer drive motor, a drive mot-or starter circuit, switch means connected to complete said starter circuit when one of said function control relays is energized, switch means to interrupt said starter circuit after the corresponding slow break relay is energized, circuit means through one of said timed control channels to retain said drive means energized fora cycle of operation, each said latch circuit including contacts on its corresponding control relay closed when said control relay is energized and including one of said timed control channels closed momentarily at the start of each cycle of operation, each said unlatch circuit including contacts on said latch relay closed when said latch relay is energized and including back contacts on its corresponding time controlled channel opened momentarily at the start of each cycle, an output circuit, a plurality of tone generators, a plurality of output paths connected to said output circuit, one of said output paths including one of said tone generators and one of said timed control channels closable during half of said cycle, another of said output paths including another of said tone generators and another of said timed control channels closable early during each half of each cycle, the remainder of said output paths each including contact means closed when its corresponding function control relay is energized and including time controlled channels and transfer contact means adapted to connect the remaining tone generators sequentially to half of said output paths during half of said cycle and sequentially to the other half of said output paths during the other half of said cycle.

References Cited in the file of this patent UNITED STATES PATENTS 2,369,662 Deloraine Feb. 20, 1945 2,388,531 Deal Nov. 6, 1945 2,529,814 Reifel Nov. 14, 1950 2,554,329 Hammond May 22, 1951 2,559,622 Hildyard July 10, 1951 2,832,060 Hendricks Apr. 22, 1958 2,919,439 Cesareo Dec. 29, 1959 2,922,151 Reiling Jan. 19, 1960 

1. A TONE SEQUENCE TIMING AND SWITCHING CIRCUIT COMPRISING A PLURALITY OF FUNCTION CONTROL CONDUCTORS ENERGIZABLE INTO A NUMBER OF CONTROL COMBINATIONS, A LIKE PLURALITY OF FUNCTION CONTROL RELAYS CONNECTED TO SAID FUNCTION CONTROL CONDUCTORS, A LIKE PLURALITY OF SLOW BREAK RELAYS EACH HAVING AN ELECTRIC LATCH CIRCUIT AND AN ELECTRIC UNLATCH CIRCUIT, A SEQUENCE TIMER HAVING A PLURALITY OF TIMED CONTROL CHANNELS AND A DRIVE MOTOR, A MOTOR STARTING CIRCUIT INCLUDING CONTACTS CLOSED WHEN ONE OF SAID FUNCTION CONTROL RELAYS IN ENERGIZED AN INCLUDING OTHER CONTACTS INTERRUPTED WHEN A CORRESPONDING ONE OF SAID SLOW BREAK RELAYS IS ENERGIZED, EACH OF SAID ELECTRIC LATCH AND UNLATCH CIRCUITS INCLUDING ONE OF SAID TIMED CONTROL CHANNELS, AND AN OUTPUT CIRCUIT INCLUDING AN OUTPUT TERMINAL, A PLURALITY OF TONE GENERATORS, A PLURALITY OF NORMALLY OPEN PARALLEL PATHS BETWEEN SAID OUTPUT TERMINAL AND SAID TONE GENERATORS, EACH SAID PATH INCLUDING ONE OF SAID TIMES CONTROL CHANNELS AND AT LEAST ONE OTHER CONTACT CONTROLLED BY SAID FUNCTION CONTROL RELAYS. 